Follow these detailed steps carefully to achieve perfectly formed, delicious cucumber avocado rolls. The key is in the preparation of the cucumber ribbons and the gentle but firm rolling technique.

1. Prepare the Cucumber Ribbons: Wash and dry your cucumbers thoroughly. Using a mandoline slicer on its thinnest setting is the most effective method for creating long, uniform ribbons. If you don’t have a mandoline, a high-quality Y-peeler will also work. Lay a cucumber flat on a cutting board and press down firmly with the peeler or mandoline, slicing from one end to the other to create a long, wide ribbon. Discard the first couple of slices that are mostly skin. Continue slicing until you reach the seedy core. Rotate the cucumber and repeat on all sides. You should have a large pile of flexible cucumber ribbons.
2. Dry the Ribbons: Lay the cucumber ribbons in a single layer on a clean kitchen towel or on paper towels. Gently pat them dry with another towel. This step is crucial; removing excess moisture prevents the rolls from becoming watery and helps the filling adhere properly.
3. Create the Avocado Filling: Cut the avocados in half, remove the pits, and scoop the flesh into a medium-sized bowl. Immediately add the fresh lemon juice to prevent browning. Mash the avocado with a fork until it reaches your desired consistency—some prefer it perfectly smooth, while others like a few small chunks for texture.
4. Combine the Filling Ingredients: Add the softened cream cheese to the mashed avocado. Mix until well combined and the mixture is smooth and creamy. Season generously with salt and black pepper to your taste. Mix one final time.
5. Prepare the Assembly Station: On a clean, flat surface like a large cutting board, lay down a sheet of plastic wrap. This is optional but highly recommended as it makes the rolling process much easier and helps create a tighter roll.
6. Assemble the Cucumber Mat: Arrange the cucumber ribbons on the plastic wrap, overlapping them by about a half-inch (or 1-1.5 cm). You want to create a solid rectangular “mat” of cucumber that is about 8 inches wide and 6 inches long. Gently press down on the overlapping seams to help them stick together.
7. Spread the Filling: Scoop about half of the avocado-cream cheese mixture onto the cucumber mat. Using the back of a spoon or an offset spatula, spread the filling evenly over the cucumber, leaving about a one-inch border along the edge farthest from you. This empty space will help seal the roll.
8. Add the Vegetable Core: Arrange a line of the julienned carrots and thinly sliced red bell pepper horizontally across the edge of the filling closest to you. Don’t overfill, as this can make rolling difficult and cause the rolls to burst.
9. Roll it Up: Using your fingertips, lift the edge of the cucumber mat closest to you and begin to roll it tightly over the filling. If you are using plastic wrap, lift the edge of the plastic wrap to help you start the roll. Continue rolling, using the plastic wrap to guide and tighten the log as you go, much like you would for a sushi roll. The motion should be firm but gentle to avoid tearing the cucumber ribbons.
10. Seal and Chill (Optional but Recommended): Once fully rolled, wrap the entire log tightly in the plastic wrap, twisting the ends to secure it. Place the wrapped roll in the refrigerator for at least 15-30 minutes. Chilling helps the roll firm up, making it significantly easier to slice cleanly.
11. Slice and Serve: Remove the roll from the refrigerator and unwrap it. Place it on a cutting board. Using a very sharp, long knife, slice the log into 1-inch thick rounds. For the cleanest cuts, wipe the blade of the knife with a damp cloth between each slice.
12. Garnish and Enjoy: Arrange the sliced rolls on a platter. Sprinkle generously with toasted sesame seeds for a final touch of flavor and texture. Serve immediately with your favorite dipping sauces.